The present invention relates to an apparatus for joining diaphragms in slotted walls which are produced in a known manner in a single or dual phase system; diaphragm sections are introduced as additional protection against seepage, and continuously the vertical edges of the diaphragm sections are interconnected.
Slotted walls are generally installed as vertical sealing measures in the ground to seal against ground water and seepage water in foundation and water construction, and for the sealing of dumps and the like. The manufacture of slotted walls, which can be installed to depths of 30 m and greater, is effected from the surface of the ground by cutting, washing, and excavating vertical, slot-like hollow spaces which are secured against collapse by a fluid-suspension filling having thixotropic properties. In the so-called single phase system, a material such as cement and/or other binders is added to the support fluid to make it possible for the latter to remain as the slotted-wall mass. In the dual phase system, the support fluid is displaced and replaced by the final slotted-wall mass, such as concrete, by filling the remaining mass from below toward the top. Depending upon the geological conditions and the projected depth, the slotted walls can be continuously constructed in a known manner slot for slot, or a pilgrim step method, with primary and secondary sheets.
To increase the water tightness of the slotted walls, dense diaphragms and/or multi-layered diaphragms are additionally installed in the slot. The multi-layered diaphragms comprise at least one permeable and one dense layer, with the permeable layer acting as a "hydraulic trap" for seepage water and diffusing media, with fluid which has penetrated being withdrawn. Various solutions have been proposed for introducing such diaphragms into a slotted wall, and for interconnecting the diaphragms.
Published European Patent Application No. 0 074 686 discloses a method for installing flexible sealing diaphragms and for connecting the thin sheets by overlapping the layers or by injecting material which hardens into the region of the vertical sheet connections. German Offenlegungsschrift No. 25 46 946 discloses a method for introducing an elastic sealing diaphragm using the pilgrim step method, with the connections of the ends of the sheet again having to be rinsed free for manufacture, whereby the hollow space of the slotted wall is temporarily not secure during the time the connection is made.
European Patent No. 23 45 983 discloses introducing a thin sheet from a vertical container which must be moved through the support fluid in the trench; the application of this method must for technical reasons be limited to very shallow slots.
The further published European Patent Application No. 00 86 001 amplifies the solution of the first mentioned patent for combining the ends of very thin sheets.
Unfortunately, none of the aforementioned proposals take into account the problem of manufacturing deep slotted walls having depths of greater than 5 m. If a thin slotted wall sheet is produced, the thin sheets must be produced with sufficient overlapping lengths, and must be protected during excavation of the next sheet from damage by the loosening, cutting, or excavating, after placement of the diaphragm in the adjacent slotted wall, the two diaphragms should be able to be permanently connected by welding, gluing, or other types of connection.
It is therefore an object of the present invention for the sealing of slotted walls by the additional installation of diaphragms, to provide apparatus for the satisfactory introduction into slotted walls of the diaphragms, and for permanently and reliably connecting the diaphragms.